Vehicle head lamp



March 22, 194 9. W. H, L D 2,465,106

VEHICLE HEADLAMP Filed June24, 1944 His A't borneg.

Patented Mar. 22, 1949 UNITED STATES PTENT OFFICE VEHICLE HEAD LAMP Wilfrid H. Lund, Beckenham, England, assignor to General Electric Company, a corporation of New York 7 Claims.

This invention relates to incandescent electric lamps and more particularly to lamps such as are used in the headlights of motor driven road vehicles to provide a beam of light sufficient to enable the driver of the vehicle to see the road clearly without at the same time dazzling a driver of an oncoming Vehicle.

Various types of lamps have been proposed for this purpose, one of the commonest being one with two filaments, one giving a long range driving beam and the other a fiat anti-dazzle beam, the former being used for ordinary driving and being out of circuit, and the latter energized when meeting an oncoming vehicle.

The object of the present invention is to provide an improved form of lamp which has a single filament so arranged with respect to the reflector that it will give an efficient flat beam for driving and at the same time will illuminate the near side of the road.

To this end this invention consists in mounting the filament in a bulb so that it is in a plane at right angles to the longitudinal focal axis of the reflector with an upper limb or leg portion situated above the horizontal plane through the said axis while this axis passes through the mid-point of a lower portion of the filament. The filament is preferably formed in a J or L shape. The upper limb of the filament may be arranged vertically or may be set at an angle to the vertical so that the light from this portion may be reflected in the required direction to illuminate the curb and side of the road.

In the drawing, Fig. l is a side elevation of a complete lamp, with a reflector shown in full lines; and Figs. 2, 3 and 4 are front elevations of various forms the filaments may take.

In the drawing l represents a lamp bulb provided with a base 2 and having a stem 3 in which leading-in wires 4 and 5 are sealed to which the coiled filament 6 is secured. Fig. 2 shows a front View of one form of filament which may be used. In this case it is substantially J-shaped, the curved leg portion of the J being about 30 per cent of the total length although this proportion may be varied. The filament is so mounted that the horizontal plane HH through the longitudinal axis AA of the reflector 1 passes through the substantially horizontal curved portion of the filament while the center of this portion is substantially at the focal point i. The filament is located in the focal plane FF of the parabolic reflector 1, that is, a plane at right angles to the axis A--A and through the focal point I. The longer arm portion of the filament extends upwardly above the plane HH and to one side of the vertical plane VV through the axis A-A. It will be obvious that in this country the filament will be so arranged that the upwardly extending portion of the filament 6 will beat the left of the-plane VV (as viewed from the rear of the reflector) to direct light downward and to the right, whereas in those countries where vehicles are driven on the left-hand side'of the road the position of the filament will be reversed so that the longer arm portion extends upwardly at the right of the plane VV to direct light downward and to the left.

The line A-A also represents the longitudinal axis of the bulb I, as well as the base 2, the filament 6 being accurately located with reference to the base, so that when the lamp is mounted in the reflector 1 the filament will be correctly located therein. However, it will be obvious that in place of a separate lamp and reflector, a unitary device of the Sealed Beam type maybe employed, such as that shown in Patent 2,148,314D. K. Wright.

In Fig. 3 a substantially L-shaped filament 6' is shown, the shorter limb being mounted in substantially the same way as the curved leg portion of the J in Fig. 2 with the axis of the reflector passing through its midpoint. Fig. 4 shows an L- shaped filament 6" in which the length of the limbs are each about 50 per cent of the total length of the filament.

The eifect of shaping and mounting the filaments as above described is that a portion of the light is projected forward as a flat topped beam parallel to the axis, the balance of the light being projected downwardly with somewhat less intensity to the side of the road, the portion coming from the upwardly extending limb of the filament being more diffused and projected to the side so that it illuminates a substantial area at the side. The proportions of the filament used for projecting these two beams may, as stated, be varied between considerable limits but I find the best results are obtained if the lower portion of the filament is between about 25 to about 55 per cent of the total length. For example, Fig. 4 shows an L-shaped filament of which about 50 per cent of its length is utilized for each beam but I have found that particularly good results are obtained especially in foggy weather by utilizing about 30 per cent for the forward beam and about per cent for the beam projected to the side.

Although I have described and illustrated a single filament lamp for anti-dazzle lighting only,

it will be understood that a second filament may be mounted in the bulb for use when driving at a high speed. In this case the second filament may be of the horizontal coiled-coil type mounted in the plane of the J or L-shaped filament and mounted just below the horizontal plane H-H, or it may be a linear filament arranged in a horizontal plane at right angles to the plane of the other filament, parallel to and just below the horizontal axis AA of the reflector and bulb. With such an arrangement it is preferable for the reflector and bulb to be fixed in a slightly tilted position in the headlamp so that the axis of the main beam is brought substantially parallel to the road surface and the anti-dazzle beam is caused to dip slightly.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a vehicle headlamp, a parabolic reflector and a concentrated filament composed of a single length of wire and consisting of a substantially horizontally extending helically coiled lower leg portion constituting a substantial part of the total length of the filament and an upwardly extending helically coiled upper leg portion, said filament being disposed in the focal plane of said reflector with the center of its lower leg portion substantially coincident with the focus of the reflector so that the said lower leg portion is located symmetrically on opposite sides of the reflector focus and extends substantially in the horizontal plane thru the reflector axis, the upper leg portion of the filament being located entirely above the horizontal plane through the reflector axis and entirely to one side of the vertical plane through said reflector axis, and connections to the opposite ends of said filament for passing current through the full length thereof.

2. The combination set forth in claim 1 wherein the filament is of substantially J -shape with the lower bent portion of the J of shallow curvature so that it is located substantially in the horizontal plane through the reflector axis.

3. The combination set forth in claim 1 wherein the filament is of substantially L-shape.

4. The combination set forth in claim 1 wherein the lower leg portion of the filament constitutes between about 25 and about 55 per cent of the total length of the filament.

5. An electric lamp for use in a substantially parabolic reflector in a vehicle headlamp with the longitudinal axis of the lamp positioned horizontally and aligned with the reflector axis, comprising a bulb and a base, and a concentrated filament in said bulb composed of a single length of wire and consisting of a substantially horizontally extending helically coiled lower leg portion and an upwardly extending helically coiled upper leg portion, said filament being disposed in a plane at right angles to the longitudinal axis of said base and bulb with its lower leg portion disposed substantially in the horizontal plane passing through said axis and extending substantially equal distances to each side of said axis and its upper leg portion located entirely above the said horizontal plane through said axis and entirely to one side of the vertical plane through said axis, and connections to the opposite ends of said filament for passing current through the full length thereof.

6. The combination set forth in claim 5 wherein the filament is of substantially J-shape with the lower bent portion of the J of shallow curvature so that it is located substantially in the horizontal plane through the lamp axis.

7. The combination set forth in claim 5 wherein the filament is of substantially L-shape.

WILFRID H. LUND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,634,528 Wood July 5, 1927 2,120,870 Roper June 14, 1938 2,142,384 Taylor Jan. 3, 1939 2,214,472 Lund Sept. 10, 1940 FOREIGN PATENTS Number Country Date 648,455 France 1928 

